We are using VMWare ESXi 3.5, and have found it quite useful for cloning a live server to then use the virtualized version to test/practice software upgrades.

The trouble is, when the virtualized version fires up, it registers itself on our domain (Active Directory), causing the original server to no longer be accessible via Windows shares. The fix is to remove the virtualized version from the domain, configuring it to use a workgroup instead, deleting the Computer account in AD, and then removing the real server from the domain and re-adding it.

Is there a better procedure?

Note, we cannot simply disconnect the virtual network from the virtualized server, as it needs to be connected to the network to actually be removed from the domain.